Investigation On Laser Welding Of Quenched 42CrMo Steel

High power laser welding has been widely used in the industry due to its high productivity and excellent weld quality. The interaction between target material and the high power laser beam is a complex, multi-dimensional, and multi-parameter system. When the power densities are greater than or equal to the order 106/cm2 the target materials are typically used in deep penetration welding, their radiated surface is molten and subsequently vaporized to form a cavity known as keyhole filled with the laser-induced plasma. This system is characterized by regions with different physical processes, such as phases changing, fluid flowing and solidification. Simultaneous occurrence of melting, vaporization, solidification is the heart of the laser beam welding process. All of these phenomena influence the absorption and reflection of the laser, the heat-transfer and the mass-transfer. Then that will affect the final capability of the welding. As a nice welding process which has been well applied, people have done too much research on this process. Up to now there is lack of a suitable mathematic model that might meet the general laser welding process.The melt metal flow, the temperature field, and the microstructure and properties of the welding joint are all important issues people care about in the welding process. In these aspects what people mostly have done are always theory analysis and simulation. Is this paper, some research work was done with purpose of making some complement to above-mentioned problem. The experiments results were taken as the main foundation in the discussion of this paper, combining with the results of the theory analysis and the numerical simulation.Because of the particular characteristic of"keyhole effects"in laser welding process, it's more difficult to study the flow simulation of the molten pool. The numerical simulation work was always carried out at the basis of simplified model. Some research was done about the fluid flow of the weld pool in this paper, with the experiments of deep penetration laser welding of sheet and thick steel by some design. The differences of the fluid flow of the weld pool among the low laser...